Carbon nanotubes can be broken down biologically

A team of Swedish and American scientists has shown that carbon nanotubes can be broken down by an enzyme - myeloperoxidase (MPO) - found in white blood cells.

- Previous studies have shown that carbon nanotubes could be used for introducing drugs or other substances into human cells. The problem has been not knowing how to control the breakdown of the nanotubes, which can caused unwanted toxicity and tissue damage. Our study now shows how they can be broken down biologically into harmless components, says Bengt Fadeel, associate professor at the Swedish medical university Karolinska Institutet in a press release.

Research has shown that laboratory animals exposed to carbon nanotubes via inhalation or through injection into the abdominal cavity develop severe inflammation. This and the tissue changes (fibrosis) that exposure causes lead to impaired lung function and perhaps even to cancer. For example, a year or two ago, alarming reports by other scientists suggested that carbon nanotubes are very similar to asbestos fibres, which are themselves biopersistent and which can cause lung cancer (mesothelioma) in humans a considerable time after exposure.

This current study shows that endogenous MPO can break down carbon nanotubes. This enzyme is expressed in certain types of white blood cell (neutrophils), which use it to neutralise harmful bacteria. Now, however, the researchers have found that the enzyme also works on carbon nanotubes, breaking them down into water and carbon dioxide. The researchers also showed that carbon nanotubes that have been broken down by MPO no longer give rise to inflammation in mice.

- This means that there might be a way to render carbon nanotubes harmless, for example in the event of an accident at a production plant. But the findings are also relevant to the future use of carbon nanotubes for medical purposes, says Fadeel.

The study was led by researchers at Karolinska Institutet, the University of Pittsburgh and the National Institute for Occupational Safety and Health (NIOSH). The findings were presented in Nature Nanotechnology.

Read the full press release >>